A color calibration chart (“color chart”) is an array of several blocks of known color values that is used to calibrate and evaluate the color in cameras and other systems capable of color reproduction. Each of the squares represent different colors that are typically used in color images, such as white, black, different levels of gray, as well as colors representing human skin, foliage, and blue sky. Color charts are typically used photography, graphic arts, electronic publishing, and video production to check cameras (still and video), printers, scanners, monitors, or any other equipment used in the color reproductions system.
A photographer will typically take a picture of a scene that includes the color chart. The photographer can do this for every picture, or for a representative picture in a sequence of pictures. In the post-processing of the image, in one embodiment, a user would manually check the color of the some or all of the color squares in the reproduced color chart and adjust the reproduced color until the color of the square matched or closely approximated the known color. In an alternate embodiment, the user would select the color chart in the image and a computer would detect the selected color chart and use this chart to calibrate the image.
However, this process requires the user to manually select the color chart, or manually check each of the squares to calibrate the image. In addition, these methods known in the art require the color chart be horizontal with the image, which means that the color chart cannot be oriented at an angle other than zero to the image.